Bought a brake light switch from painless wire ... "Brake Light Switch with 1/8'' pipe thread fitting. " Doesn't fit the 1/8" NPT port on my brake distribution block though. WTF!? No big deal, so I need an adapter. Which one? 1/8" NPT to 1/8" pipe thread ???
Are "pipe thread" and "national pipe thread" the same? I am absolutely positive it won't fit the port on the distribution block. However they are very close in diameter. Using this proportioning valve ... Summit states it has 1/8" NPT threads. Same fittings that fit this, fit the block.
NPT and pipe thread are one and the same. NPT stands for National Pipe Thread. You probably have a female 1/4" inverted flare in your brake distribution block. Look inside and you'll see the machined surface where the brake tubing flare seats. Or the male inverted flare fitting seats. If so, a 1/4" male inverted flare with 1/8" female NPT on the other end will adapt your switch. The NPT fittings are drilled straight through with the tap drill and do not have a seat. The seal comes from the tapered pipe threads.
i'd just put the brake light switch inline on the rear brake line...use a tee with 3/16" inverted flare 2 ways and a 1/8" NPT on the remaining one.....NAPA part # 652X3 ..... if you are using 1/4 brake lines,use NAPA # 652X4
[ QUOTE ] Are "pipe thread" and "national pipe thread" the same? I am absolutely positive it won't fit the port on the distribution block. However they are very close in diameter.Yes and NO. You'd be amazed how many differnt threads are out there. NPT,ISO Tapered,ISO parallel, ISO parallel gauge, SAE and on and on. But listen to C9, npt and AN flare are the standards for brake systems. It would be very unusual if it was anything else.
I've got one of them in te system on my truck and a friend told me my brake lights didn't work. I showed him that they did but it took "panic stop" pressure to make them come on. they didn't work with just cruising "one toe" braking which made them irritating for someone else caravanning behind th truck. I heard that they "lose sensitivity" as they age so I just said fuck it and screwed a '56 Chevy pickup mechanical lever switch between the floor and the brake pedal arm, now thy come on any time the pedal moves regardless of pressure, and they're only a couple or three bucks cheap.
Thanks for the replys ... That definitely got me headed in the right direction. Usually I just get the ones that look the same and seal. Never gave it much thought. Here's what I've learned ... Although a few different size AN flare and SAE inverted flare fittings share the same threads. They function differently and are not compatible. SAE flare and AN flare fitting may appear to be the same and may function identically but they are not the same. This is not to say that they won't work together. NPT threads are completely different and not compatible with SAE threads of SAE flare, inverted flare or AN flare fittings. NPT threaded fittings should always be installed with a sealant. Some of this is new to me ... some not. I know there are other types but this should cover what I'm likely to run into in in the garage. Anything else I might be missing? Thanks again.
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